Modern navigation has become an integral part of everyday life, and few people think about the complex physical processes that allow your smartphone or car navigator to accurately determine your location. Global Navigation Satellite System (GLONASS) is the Russian analogue of the American GPS, providing continuous and all-weather determination of coordinates, speed and time for land, sea and air objects. The principle of its operation is based on measuring distances from the receiver to several satellites, whose coordinates are known at any given time.
The system is based on the complex interaction of the space segment, the control segment and user receivers. Satellites, orbiting at an altitude of about 19,100 kilometers, continuously broadcast radio signals containing information about their location and exact time. A receiver, whether in your phone or your car's on-board computer, picks up these signals and calculates its position in three-dimensional space. This is not just “catching a signal”, but a complex mathematical process of trilateration.
Understanding exactly how this technology works helps you better understand the characteristics of navigation equipment and understand the causes of possible failures. The system is designed to be resistant to external influences and provide independence from foreign systems in critical areas such as transport logistics and defense industry. Let's look at the architecture and physical principle of operation in more detail.
Architecture and structure of the GLONASS system
The GLONASS system is a complex software and hardware complex, which is divided into three main segments. The space segment is a grouping of satellites distributed over three orbital planes. The control segment includes a system control center, monitoring and correction stations, as well as telemetry information processing centers. The third segment is the consumer equipment itself, which we use every day.
The entire space constellation includes 24 satellites, which provide coverage of the entire surface of the Earth. However, to operate the system in minimum mode, a smaller number of devices is sufficient. The orbits of the satellites are selected so that at any point in the world and at any time of the day there is a sufficient number of visible satellites above the horizon to determine coordinates. This ensures high service availability even in difficult geographical conditions.
The ground segment plays the role of a “think tank”, constantly monitoring the parameters of the satellites’ orbits and adjusting their course. Control Center collects telemetry, calculates ephemeris (exact satellite coordinates) and generates navigation messages, which are then downloaded on board the spacecraft. Without the constant operation of ground stations, the accuracy of the system would quickly degrade due to gravitational disturbances and other factors.
The user segment includes navigation receivers of various accuracy classes. They can be built into smartphones, car trackers, aviation equipment, or used as separate handheld devices. It is important to understand that the receiver only receives signals and does not transmit them back to the satellite (with the exception of specialized systems such as ERA-GLONASS, where there is a return communication channel through cellular networks).
Physical principle of determining coordinates
Navigation is based on the passive rangefinding method. Satellites emit radio signals at certain frequencies, and the receiver records the time of arrival of the signal from each visible satellite. Since the speed of propagation of radio waves is equal to the speed of light and is a constant, knowing the signal delay time, you can calculate the distance to the satellite. However, distance alone is not enough to determine exact coordinates in space.
To calculate three-dimensional coordinates (latitude, longitude, altitude), the receiver needs to “see” at least four satellites. Why four? Three satellites allow positioning in space to be determined (trilateration), but the clock in the receiver and the clock on the satellites are not perfectly synchronized. The fourth satellite is necessary to eliminate the desynchronization of the receiver clock relative to the GLONASS system time. This allows you to get accurate time and adjust distance calculations.
The process of calculating coordinates occurs in real time and requires significant computing power of the navigator processor. The signal from the satellite carries a navigation message containing ephemeris (orbital parameters) and an almanac (general information about the state of the entire constellation). The receiver decodes this data and substitutes it into navigation equations.
For maximum positioning accuracy, try to be in an open area. Trees, buildings, and even heavy clouds can weaken the signal or create multipath, reducing the accuracy of the location.
It is worth noting that the accuracy of location determination depends on a geometric factor known as GDOP (Geometric Dilution of Precision). If all visible satellites are clustered in one part of the sky, the accuracy will be lower than if they are distributed evenly throughout the sky. Modern receivers are able to select the best combination of satellites to minimize this error.
Code separation of channels and frequencies
One of the key features of GLONASS is the method of signal separation. Unlike GPS, where all satellites broadcast on the same frequency, but with different codes (CDMA), classic GLONASS uses frequency division (FDMA). This means that each satellite emits a signal on its own unique frequency within an allocated range. This approach allows the system to be more resistant to narrowband interference.
Signals are transmitted in two main ranges: L1 and L2. The use of two frequencies makes it possible to compensate for the influence of the ionosphere on the speed of radio waves. The ionosphere is a layer of the atmosphere that can delay signals, introducing errors into distance calculations. Since latency is frequency dependent, a receiver receiving signals on two frequencies can mathematically calculate and eliminate this error, improving positioning accuracy.
- 📡 L1 range: Basic frequency for civilian users, provides standard accuracy.
- 📡 L2 range: Used to improve accuracy and correct ionospheric delays, available in modern receivers.
- 📡 L3 band: Reserved for the COSPAS-SARSAT search and rescue system.
Modern new generation satellites (GLONASS-K and GLONASS-K2) already support code division MA (CDMA) signals similar to GPS. This is done to simplify the creation of combined receivers that can simultaneously work with signals from different navigation systems using common hardware.
Why is frequency division better in some cases?
FDMA (frequency division) makes the GLONASS system more resistant to intentional interference in a narrow frequency band. If an attacker tries to jam navigation on one frequency, he will not jam the entire system, while in CDMA systems (like GPS) the wide signal bandwidth makes him more vulnerable to broadband interference, although more efficient in the use of spectrum.
Comparison of GLONASS and GPS: what is the difference
You can often hear debates about which system is better. In fact, for the end user in modern conditions the difference is minimal, since most devices use a hybrid reception mode. However, technical differences between the systems exist and are determined by the history of their development and the underlying engineering solutions.
The main difference lies in the structure of the orbital constellation and the signal encoding method. GPS satellites are located on six orbital planes, and GLONASS on three. This affects the visibility geometry of satellites at high latitudes. For the northern regions of Russia, GLONASS often shows better results, since the satellites are higher above the horizon.
| Parameter | GLONASS (Russia) | GPS (USA) | Galileo (EU) |
|---|---|---|---|
| Number of satellites | 24 (standard) | 24-32 | 24-30 |
| Orbit altitude | 19,100 km | 20,200 km | 23,222 km |
| Circulation period | 11 hours 15 minutes | 11 hours 58 minutes | 14:05 |
| Access method | FDMA (classic) / CDMA (new) | CDMA | CDMA |
| Accuracy (civilian) | 2-6 meters | 2-5 meters | 1-2 meters |
In terms of accuracy, modern systems are approximately on par under good reception conditions. Galileo, the European system, is positioned as the most accurate for civilian use, but GLONASS wins in reliability of operation in high mountains and high latitudes. That is why in Russia it is recommended to use devices that support both systems simultaneously.
The influence of the atmosphere and terrain on the signal
The radio signal, traveling from the satellite to the receiver, travels tens of thousands of kilometers and various layers of the atmosphere. This introduces inevitable distortions. The troposphere and ionosphere slow down the signal, which is perceived by the receiver as an increase in the distance to the satellite. Humidity, pressure and solar activity can significantly affect the quality of navigation.
In addition to atmospheric effects, a serious problem is multipath. The signal may bounce off buildings, rocks, or the ground before reaching the receiver's antenna. In this case, the navigator receives a mixture of direct and reflected signals, which leads to errors in determining the location. In urban environments (“urban canyons”) this is the main reason for “jumping” points on the map.
⚠️ Attention: Metallic tinting of car windows or athermal windshield containing metal can shield the GLONASS signal. If the navigator in the cabin does not work well, try placing an external antenna on the roof or using a signal repeater.
The terrain also plays an important role. In deep gorges, tunnels, or under dense forest canopy, the signal may disappear completely or become unusable for navigation. In such cases, modern systems use inertial navigation (accelerometers and gyroscopes in a smartphone or car) to “finish” the trajectory based on the last known coordinates and current speed.
ERA-GLONASS system and commercial application
The emergency response system deserves special attention ERA-GLONASS. This is not just navigation, but a complex that allows, in the event of an accident, to automatically or manually send the coordinates of the accident and data about the vehicle to the rescue service. Since 2017, the installation of such terminals is mandatory for all new cars sold in Russia.
The ERA-GLONASS terminal constantly monitors the vehicle’s coordinates and movement parameters (overload). Upon impact, the sensors record the accident, and the terminal establishes a voice connection with the dispatcher, transmitting a data package: coordinates, time, VIN code, fuel type and number of seat belts fastened. This allows rescuers to arrive faster and know what tools may be needed (for example, if the car runs on gas).
☑️ Checking the operation of navigation in the car
In the commercial sector, GLONASS is used to monitor vehicles. Logistics companies track the location of trucks, fuel consumption and compliance with the work and rest schedule of drivers. Data is transmitted via cellular networks (GPRS/4G) to the company’s servers, allowing you to optimize routes and prevent cargo theft.
GLONASS is a strategically important infrastructure that ensures the country’s technological sovereignty and transport safety, and is not just a “satellite picture” on your phone.
Frequently asked questions (FAQ)
Do I need internet for GLONASS to work?
No, you do not need the Internet to determine coordinates. The receiver receives all the necessary data directly from the satellites. The Internet is only needed to download maps, traffic jams and voice prompts. Without the Internet, the navigator will show your point on the map, but the map must be loaded into the device’s memory in advance.
Why does the navigator take a long time to determine the location ("cold start")?
During a “cold start” (after a long shutdown or moving over a long distance), there are no current satellite almanacs in the receiver’s memory. It needs time (from 30 seconds to several minutes) to download the latest data on the position of all satellites with low data rates. During a “hot start” (if the data is current), the search takes a few seconds.
Is it possible to disable GLONASS in a car?
It is impossible to routinely disable the GLONASS module in modern cars, since it is integrated into the security system (ERA-GLONASS) and multimedia. Software shutdown is only possible when flashing, but this can disrupt the operation of security systems and void the warranty. Physically disconnecting the antenna will result in loss of navigation.
Does a magnetic storm affect the operation of the navigator?
Yes, strong geomagnetic disturbances can cause disruptions in radio communications and degrade the quality of the GLONASS/GPS signal. During periods of high solar activity, positioning accuracy may temporarily decrease, and in rare cases, the signal may disappear completely for several hours.